In the manufacture of components, such as nickel base superalloy turbine blades and vanes, for gas turbine engines, directional solidification (DS) investment casting techniques have been employed in the past to produce columnar grain and single crystal casting microstructures having improved mechanical properties at high temperatures encountered in the turbine section of the engine.
In the manufacture of turbine blades and vanes using the well known DS casting “withdrawal” technique where a melt-filled investment mold residing on a chill plate is withdrawn from a casting furnace, a stationary thermal baffle has been used proximate the bottom of the casting furnace to improve the unidirectional thermal gradient present in the molten metal or alloy as the investment mold is withdrawn from the casting furnace. The baffle reduces heat loss by radiation from the furnace and the melt-filled mold as the mold is withdrawn form the casting furnace.
When a new series or run of molds is to be cast having a different exterior shape, past practice has involved shutting down the casting furnace, cooling the casting furnace to ambient temperature, and disassembling the furnace to the extent necessary to replace the thermal baffle with a different thermal baffle designed to better accommodate the new mold shape to be cast. This is disadvantageous in a high volume production environment in that labor, time and cost of making cast components are increased.
In attempts to improve the thermal gradient, various baffle constructions have been proposed such as, for example, described in U.S. Pat. No. 3,714,977 where a movable upper baffle and fixed lower baffle are used and in U.S. Pat. No. 4,108,236 where a fixed baffle and a floating baffle below the fixed baffle and floating  on a liquid coolant bath disposed below the furnace are used.
U.S. Pat. No. 5,429,176 discloses a cloth-like baffle that has a slit or other opening with peripheral edges that engage the melt-filled mold during withdrawal from the furnace.
U.S. Pat. No. 4,819,709 discloses first and second opposing, movable heat shields having overlapping regions that define an aperture through which the melt-filled mold is withdrawn. The heat shields are movable toward or way from one another in a horizontal plane.
Howmet U.S. Pat. No. 6,276,432 (MP-205) discloses use of multiple radiation baffles wherein one radiation baffle is fixed at a lower end of the casting furnace and another radiation baffle follows the hot melt-filled mold as it is withdrawn from the casting furnace.